"We are going to be the last mass shooting," vowed Emma Gonzalez, a survivor of the mass shooting at Marjory Stoneman Douglas High School in Parkland, Florida, who spoke at a gun-control rally Saturday, three days after an armed former student killed 17 of her classmates and teachers.

Gonzalez spoke bluntly to her audience, hundreds of people who gathered at the Fort Lauderdale federal courthouse, about 45 kilometers (28 miles) from the suburb where the shooting took place.

"The people in the government who are voted into power are lying to us," Gonzalez said."We are prepared to call B.S. [point out a lie]."

"They say that tougher gun laws do not decrease gun violence," she said. "They say a good guy with a gun stops a bad guy with a gun. We call B.S."

Gonzalez said mental health — a factor President Donald Trump and other authorities had pointed to in their responses to the shooting — was not the main problem; she blamed Florida's lenient gun laws, under which the teenage shooter, Nikolas Cruz, legally purchased his weapon.

"He would not have harmed that many students with a knife," she said.

Protesters hold signs as they call for a reform of gun laws three days after the shooting at Marjory Stoneman Douglas High School, at a rally in Fort Lauderdale, Florida, Feb. 17, 2018.

Gonzalez elicited a strong response from the audience when she mentioned the amount of money politicians take from the National Rifle Association (NRA), a powerful lobbying group. "To every politician who is taking donations from the NRA," she cried, "shame on you."

Meanwhile, about 60 kilometers (37 miles) away at the Dade County fairgrounds, hundreds of gun enthusiasts attended a gun show featuring more than 100 vendors of firearms and accessories.

Show manager Jorge Fernandez told the Reuters news service that the company holding the event, Florida Gun Shows, decided against canceling the show because of financial concerns.

At the show, Adolfo David Ginarte, 30, told Reuters that it would be "un-American" to cancel the gun show because of the mass shooting. "Facts don't care about your feelings," he said. "Things are going to happen. ... This isn't the first time and, unfortunately, it's not going to be the last time."

People holding placards take part in a protest in support of gun control in Coral Springs, Fla., Feb. 17, 2018.

Joe Arrington, 29, told Reuters he did not believe more regulation would have stopped the shooting. "I think a lot of agencies didn't do their job necessarily like they were supposed to," he said.

On Friday, the FBI — the top national law enforcement agency — admitted that it ignored a tipoff about the gunman.

“Very sad that the FBI missed all of the many signals sent out by the Florida school shooter. This is not acceptable,” U.S. President Donald Trump tweeted Saturday evening. “They are spending too much time trying to prove Russian collusion with the Trump campaign - there is no collusion. Get back to the basics and make us all proud!”

The agency acknowledged it did not follow “established protocols” after receiving information about the shooter on its national tip line. The FBI said someone with a close relationship to Cruz left information on January 5 about the teenager’s desire to kill people and other disturbing details.

U.S. Attorney General Jeff Sessions responded by ordering an immediate review of how the Justice Department and the FBI respond to warnings about potential mass killers.

President Donald Trump, accompanied by first lady Melania Trump and Dr. Igor Nichiporenko, speaks to reporters while visiting with medical staff at Broward Health North in Pompano Beach, Fla., Feb. 16, 2018.

Trump visits with victims

Trump and his wife, Melania, visited Florida on Friday, to meet with law enforcement officials and some of the victims of Wednesday's shooting.

At a Broward County hospital near the scene of the shooting, Trump praised the medical staff who treated the victims, saying, "The job they've done is incredible." He also praised the speed with which first responders arrived at the school. When asked by reporters whether the nation's gun laws needed to be changed, Trump did not respond.

Trump was to spend the long Presidents Day weekend at his Mar-a-Lago resort in Palm Beach, about 55 kilometers (34 miles) from Parkland.

Cruz, who was being held at the Broward County jail without bond, has admitted carrying out the shootings with a semiautomatic AR-15 rifle, according to the county sheriff's office. Cruz, who had been expelled for disciplinary reasons last year from the school, faces 17 counts of premeditated murder.